A noticeable first sign of aging is wrinkles. According to fine wrinkle classification, primary wrinkle refers to wrinkles of 20 to 100 μm, secondary wrinkle refers to wrinkles of 5 to 40 μm, tertiary wrinkle refers to wrinkles up to 0.5 μm, and quaternary wrinkle refers to wrinkles up to 0.05 μm.
Generally, there are many methods for measuring skin wrinkles.
Furthermore, as a method for measuring skin wrinkles, Patent Literature 1 discloses a method for measuring and analyzing skin wrinkles and aging status through a skin image.
In the case of the method for measuring and analyzing skin conditions through a skin image, a problem is that it is difficult to measure latent wrinkles which are likely to develop into primary wrinkle appearing more noticeable with age although not clearly visible. Wrinkles with a minimum depth of 1 mm can be visibly detected and allow image measurement. That is, secondary and subsequent wrinkles are impossible to measure by a method through a flat image.
Accordingly, there is a need for studies of a wrinkle measuring device and a wrinkle measuring method that can accurately analyze latent hidden fine wrinkles invisible to eyes.